<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
	<meta http-equiv="X-UA-Compatible" content="IE=Edge，chrome=1">

	<title></title>
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	<style>
		@media screen and (min-width: 1200px){
			body{
				background-color: red;
			}
		}

		@media screen and (min-width: 800px) and (max-width: 1200px){
			body{
				background-color: green;
			}
		}

		@media screen and (max-width: 800px) {
			body{
				background-color: yellow;
			}
		}
	</style>
</head>
<body>
	
</body>
</html>